MARSILIA QUADRIFOLIA. FOUR-LEAVED MARSILL\. I 5 



or even men. Some families will endure for a thousand years, 

 while in the case of others a few hundred years are sufficient for 

 their rise, growth, and final decay. Our present species would 

 hardly seem to be one that is on the decline ; as, if it were, it 

 would probably not thrive and spread so freely in the Cambridge 

 location, already noticed. 



The natural order, Marsiliacca;, which takes its name from 

 this genus, was styled Hydroptcridcs, or Water Ferns, by 

 Willdenow, and this is the name adopted by Dr. Gray in his 

 " Manual of Botany." Lindley, on the contrary, who in all cases 

 endeavors to denominate the order by the name of some one 

 o-enus embraced by it, adopts tlie designation employed here, 

 which was given to the order by R. Brown in the same year in 

 which Willdenow named it Hydroptcridcs ; but in these matters 

 priority does not tell, as it docs in the case of a genus or species, 

 since the system to be followed by an author is a matter of 

 individual judgment. In the natural arrangement, the Marsi- 

 liaccce are placed nearer to the Lycopodiaccce than to any other 

 cryptogamic division. One of the genera, indeed, that of Isodes, 

 has so much the character of both, that, while many authors 

 include it in Marsiliacccc, others place it in Lycopodlaccce. The 

 chief differences between jMarsiliacciS and Lycopodiace^, as 

 defined by Lindley, is that, while the latter have their spore- 

 cases one to three celled, and their reproductive bodies similar, 

 the plants of the former have tlieir spore-cases many celled, 

 and reproductive bodies dissimilar. These spore-cases, with 

 their contents, are matters of great interest to vegetable biolo- 

 gists, some of whom, notably Braun, Esprit Fabrc, Hanstein, 

 and others, have distinguished themselves by the time and 

 research bestowed on the study of these plants. The best 

 account of them is, perhaps, found in Sachs' " Text Book of 

 Botany," altliough tlmt given in Lindley's " Vegetable Kingdom," 

 chiefly from Esprit Fabrc, v.ill be found very concise. It 

 appears from these authors that the sporocarps (Fig. i) or 

 pepper-like capsules (from which the narae of " Pcpperv/ort " 



